A German startup company, Heliatek, has developed a light, flexible, thin-film solar technology using organic solar cells that could be applied to windows or integrated into concrete facades, creating electricity-generating tinted windows and structures. Turning buildings into self-sustaining clean energy power plants could be just around the corner.

Heliatek has improved significantly on the efficiency of thin-film solar cells, with its panels reaching 8 to 10 percent efficiency compared to 3 to 5 percent for typical thin-film panels. The difference is that instead of using polymers to make the solar cells, Heliatek's are made using oligomers, shorter molecules that are more stable and can be applied more uniformly. This allows for applying the solar cells in multiple layers, making the technology more efficient.

The technology still lags behind conventional silicon solar panels in efficiency, but it's ability to generate electricity in low light and high heat -- two things conventional solar panels aren't as good at -- makes up the gap. In fact, during recent tests in Singapore, the thin-film panels generated more electricity over a month than conventional solar panels.

The most exciting part of this technology though is the applications. MIT's Technology Review reports that Heliatek is already working with a construction materials company to make its flexible panels into forms for concrete facades. At construction sites the forms will be filled with concrete to become part of a facade. The startup is also working with a manufacturer to integrate its panels into windows. The thin-film is semi-transparent, which can make tinted windows that also generate electricity leading to an application that can reduce the energy used by buildings for cooling while producing clean energy -- a true win-win.

Integrating the panels directly into buildings could be a cheaper option for builders than having to buy hardware and anchors for installing conventional solar panels.

Heliatek has already raised 28 million euros from companies like Bosch and BASF. It is currently producing the panels on a proof-of-concept line, but if it can raise 60 million more euros, it plans to build a 75 MW factory to mass produce its panels using roll-to-roll printing. With ramped up production, Heliatek sees it technology becoming cost competitive with conventional solar panels in five years.